I'm looking at the bad sections of CA-51 as posted by TheStranger last July:
An odd left entrance from Arden Way, the Marconi Curve, and Howe Avenue's short deceleration ramp and nonexistent acceleration ramp. Every urban freeway built before 1960 has issues like these.
The Bayshore and Central Freeways in SF do not have stop signs at end of ramps, and the short merge from southbound 101 to eastbound 80 isn't anywhere as bad as the Howe Avenue onramp.
Both were constructed ca. 1954. The segment of I-80 (originally US 40/50) between the Central Freeway and the Bay Bridge only has left exits westbound, none eastbound.
The section of unsigned Route 51 with the short merges, the Arden Way left-entrance...that's actually more 1940s build than anything else.
This construction reminds me of the I-80 northbound exits and entrances in Berkeley and Albany. Major ones have been reconstructed and some minor ones closed, but some remain at least last time I was there. Also the way the Nimitz used to be, before the 1990s reconstruction projects.
I think CalTrans was overreacting when they moved I-80.
Just putting the mainline for I-80 on the northern loop got a lot of the through traffic out of the most congested part of Sacramento, there was no need to suppress old I-80's interstate status entirely.
CalTrans didn't "move" I-80 for safety reasons per se.
The proposal for I-80 in the 1960s was to reroute the Interstate on a new alignment from north of E Street to the railroad tracks through North Sacramento, and then to today's Watt/I-80 light rail station - with today's Route 51 on the 1940s US 99E alignment as merely a temporary routing, likely to be demolished once the new carriageways were built. In the late 1970s, the Sacramento board of supervisors voted to cancel the new alignment and shift the funds to the light rail project instead.
THAT is why the I-80 moves ended up occurring, similar to why the 470 beltway in Denver is not a signed Interstate.
That's not to say that any of that is logical reasoning but I don't think CalTrans had a choice in the matter after the city played their hand.
Sure they had a choice, they could have left the number as is. The freeway didn't close just because the city vetoed the new alignment.
If the Capitol City Freeway couldn't be approved as I-480, I'd make it CA-480 with the east-west part as hidden I-480.
Why not just sign the non-Interstate segment as Route 51 and leave the east-west portion as US 50? To me that's simpler than attempting to assign one number for the route, when both corridors are rather seperate (the freeway into Arden, and the east-west extent of US 50 connecting West Sacramento with downtown and the east suburbs).
What percent of the traffic from the E-W portion continues to the N-S portion and vice versa? That is the first major route through the area, approximating US-40. Someone must think it's substantial traffic or they wouldn't have bothered signing it as Capitol City Freeway.
Much of route 51 was built with interstate funds, and the quality of the road even though it's not quite modern interstate is better than you would expect from just a SR number.
If the number I-880 were not available, the Nimitz would have had a few options, all with disadvantages: Leave it signed as CA-17 with some arbitrary hidden interstate number. Make it I-180 and renumber CA-180. A 4-digit interstate number. Make it I-3, along with US-101 from San Jose south to Los Angeles.
The I-180 suggestion would have never occurred, given that it was rejected outright for usage with what is now I-238 AND the west extension of I-580 in those days specifically because California had no desire to renumber the then-50 year old State Route 180 in Fresno. If one considers the removal of Route 30 for Route 210 as simply the extension of an existing route, then by that token there have been no lengthy route renumberings since 1964 whatsoever.
US 101 between Los Angeles and Novato was submitted as a potential interstate route in 1947 but rejected, and I don't know if it was ever submitted again. Creating a long-distance route just to give the Nimitz an Interstate number wasn't likely by that point in time, especially with 101 still having stoplights in the early 80s in Santa Barbara.
Like I said, all the options have disadvantages. Traffic on 101 has increased a lot since 1947, and most of rebuilding it to interstate standards was already done by the early 1980s, I think it would have been worth applying again. It still would, for that matter.
I think it IS fair to say that when Glenn Anderson stumped for today's I-105 and today's I-880 in the early 80s, it helped immensely that the number was available. We can speculate as to what would've happened had it not been, but that two-year gap between the Sacramento changes and the Nimitz's addition to the system meant that whether on the legislative or DOT end, someone was aware that 880 could be used again.
That sounds like the tail wagging the dog. Would the Feds really have said, "Yes, you have a good and needed project and we'd be happy to fund it, but
there's no interstate number available so forget it?" And, faced with losing a couple billion $ for the badly-needed Nimitz reconstruction, would California really have said "Keep your money, it's more important for CA-180 to keep its number?" Don't both parties first decide what projects to do based on costs (financial, environmental, etc.) and benefits and then assign an appropriate number?
Perhaps 238 as a unified freeway would have made better sense if the Mission Freeway were built, but since that was canceled, I don't think its status as a single route designation makes sense.
I'll even say that "I-238" and State Route 238 (as either Mission Boulevard or the unbuilt Mission Freeway) has never made sense as one route - but we can even argue that 580's segments are just as hodgepodge too.
Had the Mission Freeway been built, we would've ended up with this being more obvious - one north-south corridor (580 Macarthur Freeway/Mission Freeway Route 238) serving as an alternate SJ-Oakland route to relieve the Nimitz Freeway, and one east-west corridor from Livermore to Hayward.
Honestly I could see an argument to say, renumber 238/580/205 as just 205, the diagonal segment of 580 to I-5 as 705, and keep 580 on the Richmond Bridge and Macarthur Freeway routes, if it had to be renumbered - but I don't see the need all that strongly.
Agree that would be a possibility, but I still hesitate to renumber part of a major route as I-580. That's probably the first or second route anyone living in the bay area for the past 50 years has learned. Leaving I-238 alone is a better option.
The best solution is to sign it as CA 238 for continuity, and maintain it as a secret Interstate. You can thank me later.
No, it needs to be signed as interstate to appear as a good route for truckers, who have
to take it rather than I-580 through Oakland.
How about this: Renumber the 280/680 beltway under one number. Whichever got renumbered could then be applied to I-238.
No, that breaks both moving an existing heavily-used route, and besides you'd have to parallel routes 30 miles apart with the same route number. How confusing would that be?
I, too, think I-580 could theoretically work as a primary 2di, but it's simply the question of brand name recognition at this point. As noted, I-580 makes sense, since it connects the 5 to the 80, and it's been around for more than half a century now. I might argue that the 580 is to the Bay Area what the 405 is to Los Angeles: important routes that, for better or for worse, have earned their place into the local traffic lore.
I think the best solution is to renumber I-238 as I-480. I see no reason why this wouldn't work. The main argument I've heard is that it apparently would make natives remember the hated Embarcadero Freeway. Perhaps this is the case, but it seems like a fairly weak argument overall.
I think that would work. Locals hated the Embarcadero Freeway, but those who remember it at all are smart enough to realize I-238 isn't the Embarcadero Freeway